In typical cellular transmitter designs, various impairments [e.g. image distortion, counter-intermodulation (CIM) distortion, harmonics distortion, etc.] exist. Further, various calibrations are needed, in order to correct such impairments. With multiple calibrations involved, it may take significant factory calibration time to do all the calibrations, which increases cost.
In addition, the distortion measurements are typically performed using an on-chip measurement receiver, and some calibration techniques [e.g. third-order CIM (CIM3) calibration, etc.] may require measurement of very low levels of distortions, which may be difficult. This results in a measurement receiver that must be designed with higher precision which, in turn, requires more complicated circuit design (again, increasing cost).